Ulises Vergara

Action of Trypanosoma rangeli in infections with virulent Trypanosoma cruzi populations

In experimental murine infections with Trypanosoma rangeli it has been observed development immune response to Trypanosoma cruzi. The aim of the present work was to analyze the result of antigenic stimuli and the protective effect with T. rangeli in T. cruzi infections. Mice groups immunized with metacyclic trypomastigotes of T. rangeli (Choach -2V strain), derived from haemolymph and salivary gland and reinfected with T. cruzi virulent populations (Tulahuen strain, SA strain and Dm28c clone) from infected in vitro cells, showed decrease severity of disease outcomes, low parasitemia levels and 100% survival of all mice immunized, in comparison with groups infected only with T. cruzi populations, which demonstrated tissue affection, high parasitemia levels and the death of all animals. The above mentioned data contribute to understand the biological behaviour of T. cruzi and T. rangeli and their interaction with vertebrate host.

A study of histocompatibility-2 antigens in wild mice from Santiago, Chile

Wild mice from Santiago, Chile were tested by hemagglutination and absorption tests. Some of the wild animals were mated to Brachyury mice and their offspring were also tested by hemagglutination and absorption tests. A high frequency of H-2.5 antigen was observed. Other public antigens found less often were H-2.1, 3, and 8. Private antigens present were H-2.18, 23, 33, and 22, the last being the most frequent. Non expression of different antigens on erythrocytes was found to be a dominant trait. Antigens found were from either theD orK region of theH-2 complex. The existence of great polymorphism of H-2, the fact that the H-2.5 antigen is remarkably maintained in all the populations studied, and the absence of other H-2 antigens such as H-2.4 were confirmed. A possible correlation between lack of hemagglutinating HL-A antibodies and nonexpression of some H-2 antigens is discussed.

Serum antibodies to Trypanosoma cruzi antigens in Atacameños patients from highland of northern Chile

In the present work we have investigated the serum antibody spectrum to parasite antigens involved in human T. cruzi infection. Analysis was performed by conventional serology (IHA, IFAT and ELISA), complement-mediated lysis, anti-gal antibody assay and reactivity against recombinant and synthetic peptides and metacyclic antigens by immunowestern-blotting. All the sera showed a significant reactivity in IHA, IFAT and ELISA. We found that 84.2% of the sera showed lytic activity and thirty serum samples (78.9%) which showed a lytic activity higher than 50%, also showed anti-gal antibodies at serum dilutions higher than 1:1,600. Ninety-four percent of sera reacted with one or more of the recombinant DNA clones and 97.3% reacted with one or more of the synthetic peptides. A pool of serum samples with a lytic activity higher than 75% were able to produce 60% to 78% inhibition of cell invasion. Thirty-six of the serum samples (94.7%) were able to react by immunowestern blotting with a T. cruzi metacyclic antigen with molecular size of 70 kDa. The results obtained give preliminary information about the humoral immune response and the possible role of antibodies in protection against T. cruzi infection of chronic patients from the highlands of Chile.

Sexo del hospedero y dosis infectante de parásitos como factores en el desarrollo de la infección con Trypanosoma cruzi en un modelo murino

CONSTANZA URZUA* , MARIA ANGELICA MORALES*, ULISES VERGARA*MARIA TERESA PALAU* y CLAUDIO ZUNIGA** Departamento de Medicina Preventiva Animal, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile.Casilla 2 ,Correo 15, La Granja, Santiago, Chile. E-mail: clzuniga@uchile.clFinanciado por SIDA / SAREC.

Evolución de la infección con Trypanosoma cruzi en cepas susceptibles y resistentes de ratones

Ratones de las cepas ACA y A. Sn fueron altamente susceptibles, con un 100% de mortalidad alrededor de las 3 semanas postinfeccion (p. I), con un inoculo por via intraperitoneal de 2000 tripomastigotes sanguineos de la cepa Tulahuen de Trypanosoma cruzi, mientras que las cepas A. Sw y HTI se comportaron como resistentes con un 100% de sobrevida, pasados los 6 meses p.i. Sin embargo, los animales de las cepas resistentes mostraron niveles maximos de parasitemia significativamente mas altos que las cepas susceptibles. Se realizo un estudio histopatologico de musculo cardiaco y esqueletico de los ratones infectados. En los primeros 10 dias p.i. No se observaron diferencias claras entre cepas resistentes y susceptibles, en cuanto al dano tisular y presencia de parasitos intracelulares (pseudoquistes). Pero alrededor de la tercera semana p.i. Ya se vieron diferencias evidentes, mientras los animales de las cepas A. Sw y HTI mostraron bajos niveles de inflamacion y signos de recuperacion de las lesiones, los ratones ACA y A. Sn evidenciaron un progresivo aumento del dano tisular, aunque no se observaron, en este momento, formas sanguineas ni intracelulares del parasito. Muestras de suero de los ratones infectados fueron probados por un ensayo inmunoradiometrico (IRMA), para analizar la reactividad contra los antigenos recombinantes 1, 2, 13, 26, 30, 36 y SAPA de T cruzi. Todos los sueros solo mostraron reconocimiento de las proteinas 13 y SAPA, sugiriendo que esta reactividad no pareciera estar relacionada directamente con el fenomeno de resistencia o susceptibilidad a la infeccion con la cepa Tulahuen de T cruzi, en el modelo murino.

INFECCION EXPERIMENTAL CON Trypanosoma cruzi EN MACHOS Y HEMBRAS DE TRES CEPAS DE RATONES

Se inocularon 3 cepas de ratones, machos y hembras, con 2.000 trypomastigotes sanguineos del clon Dm 28c de Trypanosoma cruzi. Los ratones HTI de ambos sexos se comportaron como resistentes, en cambio, murio el 100% de los animales de las cepas A/Sn y AKR entre los 30 y 50 dias post-infeccion, respectivamente. En las tres situaciones se observaron diferencias significativas en los niveles maximos de parasitemia entre machos y hembras, teniendo los primeros niveles mas altos. Los sueros de los ratones infectados obtenidos a distintos tiempos post-infeccion, se probaron con una bateria de antigenos recombinantes de T. cruzi. Los sueros de los ratones A/Sn y AKR mostraron reactividad preferencial. Con los antigenos recombinantes SAPA y 13. Los sueros de los ratones HTI reconocieron ademas de SAPA y 13, al antigeno recombinante 36 y tardiamente al antigeno 1. En cuanto al sexo, la unica diferencia parece ser los niveles de parasitemias, pero este hecho no se refleja en diferencias a nivel de susceptibilidad o resistencia, como tampoco en el reconocimiento de los antigenos recombinantes

Mouse Slp: female expression due to a dominant non-H-2 gene in wild mice.

The S region of the H-2 complex of the mouse controls the serum levels of two proteins that are closely related structurally and antigenically: Ss, which is the fourth component of the complement system (C 4), and Slp, which does not have C 4 activity and whose function is unknown (Curman et al. 1975, Lachman et al. 1975, Meo et al. 1975, Carrol and Capra 1978, Ferreira et al. 1978). The Ss protein is present in either high levels (Ss-H) or low levels (Ss-L) in all strains of mice while the Slp protein generally occurs only in males of some inbred strains (Hansen and Shreffler 1976, Shreffier 1976, Brown and Shreffler 1980). In the study of the H-2 complex of wild mice, one Sip-positive female was detected and the present report shows that the Slp production in this female is apparently controlled by a dominant non-/-/-2 gene that permits the expression of the H-2-1inked structural gene. A group of 23 wild mice were trapped in Buin, a rural area 40 km from Santiago where the H-2 typing of another group of wild mice was previously described (Pizarro et al. 1977). The mice were brought into the laboratory and tested after they had been kept in captivity for two months. The Ss and Slp typing was done by rocket immunoelectrophoresis using rabbit anti-mouse Ss antisera prepared according to Ferreira and Nussenzweig (1979), and mouse alloantisera to Slp prepared according to Passmore and Beisel (1977). These sera were kindly provided by Dr. G. Hoecker (Universidad de Chile) who obtained them from Dr. A. Ferreira (New York University). Rocket immunoelectrophoresis (RIE) was performed as previously described (Weeke 1973) with 5 x 5 cm glass plates and barbital calcium lactate buffer pH 8.6 containing 0.023 M sodium barbital, 0.037 M barbituric acid, and 0.0009 M calcium lactate. The levels of antigen measured by RIE were calculated by comparing the height of the peaks generated by the samples with that of B10.D2 (Ss-H, Sippositive) and C3H (Ss-L, Sip-negative) male sera, which were included in each plate. Among the wild mice, one Sip-positive female was detected by rocket immunoelectrophoresis. She was found to be of the Ss-high phenotype like all of the

ESTUDIO HISTOPATOLOGICO EN RATONES INFECTADOS EXPERIMENTALMENTE CON Trypanosoma cruzi

Se infectaron cuatro cepas de ratones, machos y hembras, con 2000 trypomastigotes sanguineos de la cepa Tulahuen de Trypanosoma cruzi. Los animales de las cepas A.Sw y HTI se comportaron como resistentes y los de las cepas A/Sn y HTG como susceptibles, independiente del sexo de los animales infectados. En los casos de las cepas A.Sw, HTG y HTI se observo niveles significativamente mas altos de parasitemia en los machos. A nivel histopatologico el dano tisular no presenta inicialmente diferencias significativas entre cepas resistentes y susceptibles, sin embargo, con el tiempo se puede ver que en los animales resistentes se inducen fenomenos de reparacion del dano, en cambio en los ratones susceptibles las lesiones parecen aumentar a pesar de no observarse parasitos intracelulares o circulantes

Trypanosoma rangeli infected mouse sera reactivity with Trypanosoma cruzi synthetic peptides

In man, differential diagnosis of Trypanosoma cruzi and Trypanosoma rangeli infections represents a serious problem, not only because both parasites present similar geographical distribution, the same hosts and sometimes the same insect vector, but also because they have common antigen determinants. In this work IgM and IgG humoral responses to T. cruzi syntethic peptides in mice infected with T. cruzi and with T. rangeli were analysed. In a immunoradiometric assay ( IRMA ) 6 syntethic peptides were used, denominated as clones 1, 2, SAPA, 13, 30 and 36. The results showed that sera from infected mice with T. rangeli recognized all peptides derived from T. cruzi proteins, at IgM as well as IgG level. Reactivity with peptide SAPA is discussed as previous work indicated that SAPA is not codified in the T. rangeli genome. Our results support the suggestion that crossed reactions are due to the fact that both parasites present common antigens.

tch, tsf AND tte: THREE INDEPENDENTLY ISOLATED t HAPLOTYPES IN THE MOUSE

Three recessive lethal t haplotypes have been independently isolated from widely separated Chilean wild mouse populations. They do not complement one another, have similar transmission ratios and suppress recombination. We do not know at present if they belong to a previously described complementation group or if they define a new one.